My youngest son is the result of a vasectomy reversal. I'm not sure as to the expenses because it was covered by our insurance at the time. My husband had a reversal after our second son was born (my oldest two sons are not my biological children). After we were married we decided to give having another child a try. He had the reversal after 11 and a half years. Your chances of it working after 10 years drop by 50%.. and it doesn't start out at 100%. So the dr told us to give it two years if there's no baby, there isn't going to be. We stressed every month for almost 2 years when I started my period and everyone asking if we were pregnant yet. Finally we decided it wasn't going to happen, told our family to please stop asking cause it apparently didn't work for us. We stopped worrying and thinking about it and I got pregnant. So point being... yes reversals can work, and they work alot better when you're not stressed and "trying" to get pregnant lol
Considering the age of your children the success rate should be very high. It also depends on the procedure and how much of the tube was actually cut away. Fair warning for your husband, the reversal is more painful than the vasectomy. Basically because they have to pull on the vas deferens tubes to get them to rejoin again.
P.S. After I posted this I was reading some of the responses and was rather annoyed. To some of you people: obviously the decision to have the vasectomy was a joint decision not just her husband's, and the decision to have reversal is also, obviously, a joint decision. She didn't ask for advice on her and her husband's decision.